First ionization potential bias evolution in an emerging active region as observed in SPICE synoptic observations

¹ Southwest Research Institute Boulder CO 80302, USA
² Smead Aerospace Engineering Sciences Department, University of Colorado Boulder Boulder CO, USA
³ University College London, Mullard Space Science Laboratory Holmbury St. Mary Dorking Surrey RH5 6NT, UK
⁴ Space Science Division, Naval Research Laboratory Code 7684 Washington DC 20375, USA
⁵ ETH-Zurich, Hönggerberg Campus HIT Building Zürich, Switzerland
⁶ PMOD/WRC Dorfstrasse 33 7260 Davos Dorf, Switzerland

^★ Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 17 February 2025
Accepted: 3 December 2025

Abstract

Aims. We investigate the time evolution of relative elemental abundances in the context of the first ionization potential effect focusing on an active region (AR). Our aim is to characterize this evolution in different types of AR structures as well as in different atmospheric layers. We wish to assess how the measured changes relate to different magnetic topologies by computing abundance enhancement in different conditions using the ponderomotive force model.

Methods. Leveraging SPICE (Spectral Imaging of the Coronal Environment) spectroscopic observations of extreme ultraviolet lines from ions formed across a broad temperature range – from the upper chromosphere to the low corona –, we performed relative abundance ratios following differential emission measure analysis. This methodology yields abundance maps from low, intermediate, and high first ionization potential elements.

Results. We obtained the temporal evolution of a number of abundance ratios for different structures on the Sun. We compared these results with the outcomes of the ponderomotive force model. We find good correlation between the model and our results, suggesting an Alfvén-wave driven fractionation of the plasma. Fan loops, loop footpoints and AR boundaries exhibit coronal abundances, while the AR core shows more photospheric-like composition. A slow and steady increase in the Mg/Ne first ionization potential bias values is observed, starting around 1.5 and increasing by about 50% after two days. The S/O evolution coupled with the model provides evidence of resonant waves fractionating the plasma in transition region structures.